In the past, iron-nickel alloys have been developed having extremely low thermal expansion coefficients which enable them to be used over wide temperature ranges without losing strength and without any substantial change in elasticity. Examples of such alloys are given in U.S. Pat. Nos. 3,157,495 and 4,006,011 and typically contain controlled amounts of cobalt, columbium and titanium. They are used in such applications as rocket engine parts and the like which must have superior resistance to thermal fatigue. A difficulty with alloys of this type, however, is their notch sensitivity and severe microshrinkage upon cooling from the molten state. As a result, they have not been used in the cast form.